Stabilized foam for medical PSA substrate

ABSTRACT

The present invention provides a stabilized foam having a crosslinked closed cell polyolefin foam having a top and a bottom surface; a stabilizing layer disposed onto at least one of the top and the bottom surfaces of the crosslinked closed cell polyolefin foam; and an adhesive layer disposed onto at least one of the top or the bottom surfaces. Also provided is a method of preparing the stabilized foam, a method of treating a wound, scrape, abrasion or skin puncture, a method of maintaining cleanliness of an operation incision site, suture site, catheter insertion site, or an intentional skin breach site, a method of monitoring electrical impulses during EKG or delivering electrical impulses in a TENS or biofeedback therapy, and a method of softening the collagen deposits on a scar and reducing the raised or keloid portion of the scar over time.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a stabilized foam. More particularly,the present invention relates to a stabilized foam suitable for use inmedical and skin contact applications, having a crosslinked closed cellpolyolefin foam, at least one stabilizing layer and at least oneadhesive layer.

2. Description of the Related Art

For a variety of medical and skin contact products including first-aidbandages, tapes, absorbent dressings, wound covers and closures, scarreduction therapy pads, electrode grounding pads and drug deliverypatches, foam is used as the exterior layer away from the skin. A skincontact adhesive is applied to this foam to provide adhesion to theskin. Many adhesives are in use and include acrylics in hot melt,solvent solution or aqueous suspension, synthetic block copolymer andother hot melts, silicone gels and silicone from solvent or hot meltsystems. Often such foam films are white, tan or sheer in color and arefrequently perforated for air breathability. They can also be printedwith a design or logo.

An alternative unstabilized polyolefin foam material is presently inlimited use. Other existing foams generally used in this application aretypically vinyl or PVC based and when manufactured are cast on a releaseliner. This release liner provides stability to the foam while in theadhesive coating operation and possibly subsequent convertingoperations. The release liner can also be embossed which imparts thepattern to the foam being cast upon it.

There are several disadvantages to the use of PVC foams. PVC or vinylfoams have a plasticizer content that is inherent to the manufacturingprocess of PVC foam. These plasticizers have been investigated forpossible medical safety risk with a concern of migration from the foaminto the skin. The plasticizers in PVC also can migrate from the foaminto the adjacent adhesive and/or release liners. There are regulatorylimits to the use of PVC in Japan; similar restrictions are reportedlyunder consideration in Europe. PVC foams and films are under elevatedsafety scrutiny and medical device designers are receptive toalternative products.

Additionally, when bandages and tapes utilizing PVC foam are sterilizedor simply aged, shrinkage of the foam is often observed. This shrinkagecan be minor and is generally considered to be only a visual problem.But it can also be a more severe problem that can cause finished productrejections and/or can cause a visible exposed adhesive edge resultingfrom the PVC foam shrinking while the adhesive layer remains stable. Thelarger the die cut product, the larger the shrinkage is. Shrinkage inthe PVC foam can also cause curling or rolling of the finished product.Shrinkage of any degree is not desired.

The plasticizer used in the PVC can also limit the selection of fillersand “actives” that could potentially be incorporated into or on thefoam. Additionally, via a process known as “plasticizer migration” thePVC plasticizer can flow to adjacent materials and effectively limitswhat materials and adhesives can be adjacent to it. A typical problem issoftening and expansion, even wrinkling, of an adjacent layer.Conversely, the PVC foam can absorb and “wick” oils and plasticizersinto it from certain adhesives, especially hot melt adhesives containingoils. When this occurs, the PVC foam grows and changes shape over time.

Polyolefin (PO) foam is an alternative to PVC foam. This material isrelatively low cost and can be manufactured in large volumes. However,it also has several undesirable properties. Polyolefin foams tend to bestiff and rigid when flexed and are easily torn or ripped. The polymersused in PO foams are cross-linked via application of electron-beam(e-beam) energy during manufacture. It is believed that thiscross-linking leads to the stiffness and tearing tendency. In summary,if polyolefin foam is made to be thin and conformable, it is very weakand tears. Conversely, if thickness or density is increased to decreasetearing, the foam is stiff and not conformable to the skin.

Stiffness is generally not a desired property for foam used in a skincontact application. Flexibility and conformability are desirableproperties to facilitate movements, such as, the flexing of finger,wrist, or elbow joints. Thus, despite the presence of an adhesive layer,stiff foams do not remain attached during flexing and, as a result,tends to lift off the skin.

Resistance to tearing is also critical. Of particular concern is thetearing when the foam is stressed in the cross-machine (CD) direction.Through polymer orientation in the manufacturing process, strength isconcentrated in the machine direction (MD). Although strong in themachine-direction, so is the tendency to tear. For many potentialend-use applications, this pronounced tear is a problem. Ideally,balanced stretch and tear properties are desired. First-aid bandages,tapes, wound covers or closures are not physically large, often ¾ inchto 2 inch at their narrow dimension. When the product is applied adegree of tension is required to attach and adhere it in place. Thistension promotes tearing in PO foams. Often the PO foam is perforated toallow breathability. The physical apertures of the perforation impartedfor breathability additionally weaken the foam and further promotetearing.

The low level of dimensional stability makes PO foams difficult toprocess through converting operations. Tensions within the unwindingpull-roll and die cutting zones result in elongation often with delayedrecovery or no recovery. This tension and stretch imparted in the foamwill often relax after processing and result in differential shrinkageof components and/or curling of the finished products. As thinner gradesof PO foam are converted, the stretch and curling problems becomeexaggerated.

PVC foam has an appealing hand, good conformability and stretch recoverycharacteristics that make it suitable for bandages. Both PVC andpolyolefin foams are economical products to manufacture.

Thus, there is a need in industry to identify alternatives to PVC andpolyolefin foams that overcome these problems.

There have been efforts in recent years to locate an alternative to PVCfoam to resolve the plasticizer and shrinkage problems withoutsacrificing the low cost or the appealing stretch/recovery properties.Alternate foams, such as, polyvinyl alcohol (PVA) foam, polyurethanefoam, polyolefin foam, and the like, have also been evaluated. However,there have been no suitable alternatives found to date that meet all thedesign criteria listed above. The reasons for the absence of suitablealternatives include the following:

-   -   (1) polyvinyl alcohol foams are difficult to manufacture and not        readily commercially available;    -   (2) polyurethane foams offer good physical properties but are        very expensive;    -   (3) silicone foams also offer good properties but are more        costly than the polyurethanes; and    -   (4) although polyolefin foams are relatively low cost, they have        poor dimensional stability, exhibit stretching especially when        thin and tend to rip or tear when stressed, particularly when a        bandage is removed from a wound. Thus, because of their        stiffness, polyolefin foams generally have poor adhesion to the        skin and are not conformable to the skin when flexed.

The stabilized polyolefin foam according to the present inventionprovides an attractive and economical alternative to PVC and otherfoams.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a stabilized foamthat exhibits softness and conformability properties approaching or evenexceeding those of PVC.

It is another object of the present invention to provide a method ofpreparing such a stabilized foam.

It is still another object of the present invention to provide astabilized foam that is suitable for use in both medical and skincontact applications.

It is yet another object of the present invention to provide stabilizedfoam wherein the adhesive layer can be applied as a solvent-based,aqueous hot melt or co-extruded adhesive.

It is yet another object of the present invention to provide astabilized foam that exhibits improved stability while resistingstretching when transported through slitting, perforating, die cutting,lamination, packaging or subsequent processing operations generallyknown as converting operations.

It is a further object of this invention to provide a stabilized foamthat exhibits improved processing.

It is still a further object of this invention to provide a stabilizedfoam, which does not require the use of potentially hazardousplasticizers.

It is yet a further object of the present invention to provide astabilized foam which does not have some of the disadvantages associatedwith PVC foams or non-stabilized polyolefin foams.

It is another object of the present invention to provide a method oftreating a wound, scrape, abrasion or skin puncture.

It is still another object of the present invention to provide a methodof maintaining cleanliness of an operation incision site, suture site,catheter insertion site, or an intentional skin breach site.

It is yet another object of the present invention to provide a method ofmonitoring electrical impulses during EKG or delivering electricalimpulses in a TENS or biofeedback therapy.

It is a further object of the present invention to provide a method ofsoftening the sar tissue and collagen deposits within a scar andreducing the raised or keloid portion of the scar over time.

These and other objects and advantages of the present invention areachieved by the use of the stabilized foam having a crosslinked closedcell polyolefin foam having a top and a bottom surface; a stabilizinglayer disposed onto at least one of the top and the bottom surfaces ofthe crosslinked closed cell polyolefin foam; and an adhesive layerdisposed onto at least one of said top and said bottom surfaces of saidcrosslinked closed cell polyolefin foam or onto at least one of saidstabilizing layers.

Such a stabilized foam can be prepared by a method having the steps of:

-   -   providing a crosslinked closed cell polyolefin foam having a top        and a bottom surface; applying a stabilizing layer onto at least        one of the top and the bottom surfaces of the crosslinked closed        cell polyolefin foam; and applying an adhesive layer onto at        least one of said top and said bottom surfaces of said        crosslinked closed cell polyolefin foam or onto at least one of        said stabilizing layers.

The method of treating a wound, scrape, abrasion or skin puncture, themethod of maintaining cleanliness of an operation incision site, suturesite, catheter insertion site, or an intentional skin breach site, themethod of monitoring electrical impulses during EKG or deliveringelectrical impulses in a TENS or biofeedback therapy, and the method ofsoftening the scar tissue and collagen deposits in a scar and reducingthe raised or keloid portion of the scar over time can all be achievedby employing, as needed, the stabilized foam according to the presentinvention.

These and other objects and advantages of the present invention can beunderstood by the detailed description that follows.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention provides low cost stabilized foam to the medicaland first aid markets. The stabilized foam does not have any plasticizerso that no potentially harmless migration can occur.

The stabilized foam according to the present invention is heatstabilized and crosslinked so that it can resist shrinkage. Thestabilized foam exhibits attractive stretch/recovery properties. Alsothe starting material, which is a crosslinked closed cell polyolefinfoam, can be obtained directly from the manufacturer.

The crosslinked closed cell polyolefin foam is commercially available inwide widths and can be pigmented in almost any color.

The crosslinked closed cell polyolefin foam can be coated with anadhesive and can be perforated using conventional equipment to enhancebreathability.

It can be produced in a variety of thicknesses and densities.

Manufacture of the Stabilized Foam

The manufacture of the “stabilized foam” is a multi-stage operation.There may be variations around this manufacturing technique however thegeneral manufacturing process is described below.

In the first stage of the operation, a polyolefin, such as, closed cellpolyolefin foam, is provided. Preferably, the closed cell polyolefinfoam has a thickness about 0.010 inches to 0.050 inches and has adensity about 4 pounds/cubic ft (pcf) to about 20 pcf.

The closed cell polyolefin foam is prepared by extruding a mixture ofpolyolefin polymer(s) and a gas releasing blowing agent to produce afoam-forming mixture as a precursor thick film.

The resulting precursor foam-forming mixture is thereafter wound on aroll to form a wound foam-forming mixture in the form of a film having athickness from about 0.0050 inches to about 0.025 inches.

The wound precursor foam-forming mixture that had been extruded to forma film is then exposed to heat in an oven, at a temperature from about100° C. to about 250° C., whereupon the blowing agent expands to formthe closed cell polyolefin foam.

The closed cell foam thus formed is exposed to a high-energy electronbeam source to promote crosslinking and produce a crosslinked foam film.Other sources of crosslinking energy include gamma radiation and intenseUV light.

After crosslinking, the closed cell polyolefin foam product preferablyis about 0.010 to about 0.050 inches thick with a density about 4 pcf toabout 8 pcf, typically about 6 pcf, and is typically pigmented to awhite, tan or sheer color.

Closed cell polyolefin foams are commercially available from a varietyof sources and manufacturers. Voltek and Rogers Corporation are bothmanufacturers of this type of foams. Closed cell polyolefin foamssupplied by Voltek and Rogers and other manufacturers are suitable foruse as the closed cell polyolefin foam in the method of the presentinvention.

Although the formation of the closed cell polyolefin foam issubstantially complete at this stage, the foam is structurally weak andcan tear readily, especially in the machine-direction. It is alsounacceptably stiff.

While selecting the PO polymer(s) for the initial blend, a percentage ofmetallocene catalyzed PO polymer may be utilized. As metallocenecatalyzed Polyethylene polymers are much softer and more elastic thanconventional PO polymers, the resultant foam would be a softer and moreconformable foam. It is recognized that via blending and mixing two ormore different olefin raw materials any number of physical propertymodification may be achieved.

The overall composition and construction of the foam, ie., color,density, thickness, polymer blend, or surface appearance, can betailored to the specific end use requirements.

In the second stage of the operation, a stabilizing layer of HDPE,LLDPE, LDPE, ULDPE, metallocene catalyzed Polyethylene Polymer (mLLDPE),polyurethane, vinyl acetate, silicone gel, silicone rubber or othersuitable polymer is applied onto at least one surface, i.e., the topsurface and/or the bottom surface, of the crosslinked foam film andthereafter laminated or bonded onto the crosslinked foam film tostabilize the crosslinked foam film.

The stabilizing layer can be a single layer or it can be a plurality oflayers, including co-extruded polymers.

Preferably, the stabilizing layer is a thin layer having a thicknessfrom about 0.0005 inches to about 0.005 inches.

The stabilizing layer can be pressed against an embossed or patternedsurface while molten to impart a permanent surface appearance in thecoating.

In the practice of the method of the present invention, the stabilizinglayer is adhered onto the crosslinked foam by a variety of techniques,including techniques, such as, adhesive, thermal, radio frequency,ultrasonic, electrostatic attraction and chemical bonding.

It has been found that if a layer of HDPE, LLDPE, LDPE, ULDPE,metallocene catalyzed PE polymer (mLLDPE) polyurethane, vinyl acetate,silicone gel or silicone rubber is present, i.e., is adhered to thefoam, the tensile, tear and streetch/recovery properties are greatlyimproved. The stabilizing layer is generally extrusion coated onto thefoam. The polymer(s) are processed through conventional screw extruders,slot extrusion dies and nip rollers are used during this process.

Additionally, this stabilizing layer provides a good base upon which toanchor the pressure sensitive adhesive (PSA) materials. Foam tearing anddelamination routinely observed with conventional olefin foams ismitigated via the use of a stabilizing layer

The stability imparted by this stabilization technique also enhances theability to process the stabilized foam through printing, impregnation,die cutting, lamination and similar converting processes

The properties of the stabilizing layer and the foam complement eachother such that the presence of a stabilizing layer on the crosslinkedfoam film stabilizes the overall stabilized foam. By adding astabilizing layer to the crosslinked foam film, properties comparable tothose of PVC foam can be achieved without the disadvantages associatedwith PVC foams. Thus, the stabilizing layer provides strength to thefoam allowing a thinner and softer foam to be utilized while achievingdesired physical properties.

The preferred stabilizing layer has a thickness from about 0.0005 inchesto about 0.0025 inches and is an extrusion coating of a polyolefin ormetallocene PE film.

The composition of the stabilizing layer can be tailored to the specificend use requirements.

In the third stage of the operation, pressure sensitive adhesive (PSA)materials are introduced onto at least one layer. Several adhesivealternatives are generally available. Acrylic adhesives in a solventthat is removed via the application of heat, acrylic adhesives in anaqueous solution that are also dried via the application of heat or HotMelt adhesives that are melted and applied via roll coating, extrusionor slot dies or pattern coating. Silicone adhesives are also availablein solvent, hot melt and two-part reactive versions.

Hot melt adhesives are solvent-free adhesives that arecharacteristically solid at temperatures below about 180° F., are lowviscosity fluids above 180° F., and rapidly set upon cooling.

A variation of the hot melt adhesive application involves theco-extrusion of the adhesive layer at the same time the stabilizinglayer is applied. This saves time and cost and also minimizes anypotential for delamination of the adhesive.

The effective amount of PSA material is about 20 gsm to 80 gsm and isadjusted to match the requirements of the final application. Morepreferably, the effective amount PSA material is about 30-70 gsm.

Should a silicone gel or rubber be used as the adhesive layer, thethickness and weight can be far greater. Thicknesses of 0.007 to 0.050are generally preferred.

The side of the stabilized foam to which adhesive will be applied iscorona treated for improved anchorage or adhesion of the adhesive layerto the stabilized foam. Corona treating is a widely used process bywhich electrically charged plasma is generated and exposed to a surface.The plasma disrupts and “etches” the treated surface and makes availablebonding sites for attachment of the adhesive.

The adhesive can be either directly or indirectly coated onto astabilized layer or a non-stabilized layer.

The preferred adhesives include 100% solids hot melt adhesives, such asthose supplied by HB Fuller, Henkel, ATO Findlay and others.

The heated adhesive is typically delivered to a slot die using anextruder and/or a gear pump and the adhesive is cast onto, for example,about 42-lb/ream silicone coated Kraft paper at an adhesive thicknessfrom about 0.0015 inches to 0.005 inches.

In the indirect coating process, the stabilized foam, which includes thefoam and the stabilizing layer, is then squeezed into this adhesivelayer. When the foam and liner are peeled apart, the adhesive remainsattached to the foam substrate, not the release liner.

In this approach, adhesive application speeds of over 200 fpm and up to600 fpm are typical.

In the direct coating process, the adhesive layer is placed directlyonto the stabilized foam, which includes the foam and the stabilizinglayer, and thereafter the top surface of the stabilized foam isoptionally further coated with an additional adhesive layer and liner ifrequired.

Typically, the stabilized foam and adhesive laminate described aboveutilizes a release liner, typically silicone coated paper or film.However, if a silicone gel or silicone adhesive is used, the use of arelease liner is optional as a self-wound product is possible without arelease liner because the polyolefin foam is non-adherent to, acts as, arelease liner to the silicone gel or silicone adhesive.

Optionally, a patterned or discontinuous adhesive coating can also beapplied onto the stabilized foam.

Perforation of the film/foam/adhesive laminate is often desired forimproved breathability. Both hot needle and ultrasonic perforations aresuitable and work well with these materials. Perforation can occurbefore adhesive coating or after. An alternate technique involves makingsmall cuts or slits into the foam to allow airflow. Depending on thelength, orientation and frequency of these slits, when pulled, the foamcan physically expand and not only allow airflow but also a large degreeof physical elongation. These slits would generally be made on the foamstructure after the stabilizing and adhesive layers are applied.

Adhesive coated stabilized foam is often perforated and slit to narrowwidths in the ¾ inch to 4 inch range. These slit rolls are furtherprocessed via the application of other materials such as absorbentnon-adherent pads composed of fibers or foam, “active” treated pads thatmay have antibacterial or antimicrobial properties and release liners.They can be wound in a roll as a tape or die cut into a shape such as afinger bandage, or 4 inch×4 inch dressing.

Additionally, the stabilized foam can be used as a substrate to castsilicone gel materials. The silicone is used as a soft adhesive whilethe stabilized foam delivers the physical structure required forhandling and use of the final product.

The stabilized foam is thermoformable and can be molded into a shape oradditionally laminated to a substrate. The selection and thickness ofthe polymer used in the stabilizing layer can play an important roll inthe properties of the structure following thermoforming. For example, alow melt point ethylene that can optionally contain a percentage ofvinyl acetate polymer can be used both as the stabilizing layer and as abonding layer to provide adhesion to an adjacent substrate.

S7o Further Advantages of Present Invention Include:

-   -   (1) the stabilized foam according to the present invention        exhibits properties generally comparable to those of PVC;    -   (2) the stabilized foam according to the present invention        exhibits minimal shrinkage when sterilized or kept in storage;    -   (3) the stabilized foam according to the present invention is        suitable for use in skin contact applications;    -   (4) the adhesive layer in the stabilized foam according to the        present invention can be applied as a solvent-based, aqueous,        hot melt, extruded or co-extruded adhesive or silicone gel;    -   (5) the stabilized foam according to the present invention does        not require the use of plasticizers which, if present, can        migrate out of the foam onto the skin, adhesive or liner and        cause a potential health hazard;    -   (6) the stabilized foam according to the present invention        offers increased dimensional stability and strength thereby        allowing easier handling and processing;    -   (7) the stabilized foam according to the present invention        allows the treatment of a patient's wound, scrape, abrasion or        other skin puncture with a foam finger bandage, butterfly        dressing, tape or other protective device without the need for        PVC foam while maintaining acceptable conformability properties;    -   (8) the stabilized foam according to the present invention        allows a method of treating a patient's operation incision site,        suture site, cathetr insertion point, or other intentional skin        breach with a shower water block system to maintain incision        cleanliness while the patient washes or is in hydrotherapy. Such        adherent water block dressings are physically large enough to        completely cover the affected area and withstand the physical        demands of washing, showering and swimming; and    -   (9) the stabilized foam according to the present invention        allows a method of patient treatment utilizing electrical        grounding pads designed to monitor electrical impulses (EKG        pads) or to deliver electrical impulses (transcutaneous muscle        stimulation (TENS) or biofeedback therapy) with a foam device        without the use of PVC foam while maintaining acceptable        conformability properties.

The present invention also provides a method of treating a wound,scrape, abrasion or skin puncture in a patient. The method includes thestep of contacting the wound and a first-aid foam finger bandagedressing, butterfly dressing or tape having a stabilized foam accordingto the present invention. The stabilized foam can further have anabsorbent, non-adherent and/or antimicrobial fibrous pad placed towardthe wound for cleanliness, comfort and infection control. This methodcan be used without the need for PVC foam while maintaining acceptableconformability properties.

The present invention further provides a method of maintainingcleanliness of an operation incision site, suture site, catheterinsertion site, or an intentional skin breach site in a patient. Themethod includes the step of treating the site with a shower water blocksystem having stabilized foam according to the present invention.

Such adherent water block dressings are physically large enough tocompletely cover the affected site and effectively block the penetrationof water while used in showering, washing and swimming.

The method can further employ an absorbent, non-adherent and/orantimicrobial fibrous pad placed toward the wound for cleanliness,comfort and infection control.

The present invention still further provides a method of monitoringelectrical impulses in a patient during EKG or delivering electricalimpulses to a patient in a TENS or biofeedback therapy. The methodincludes the step of treating the patient with a foam electricalgrounding pad or a foam device having stabilized foam according to thepresent invention.

This method treats a patient with foam electrical grounding padsdesigned to monitor electrical impulses (EKG pads) or to deliverelectrical impulses (TENS or biofeedback therapy) with a foam devicewithout the use of PVC foam while maintaining acceptable conformabilityproperties via the use of such stabilized foam. For patients withsensitive skin, a soft and easy-peel adhesive can be utilized.

The present invention still further provides a method of softening thescar tissue and collagen deposits in a scar and reducing the raised orkeloid portion of the scar over time. The method includes the step oftreating said scar with stabilized foam according to the presentinvention.

Preferably, the adhesive layer in the stabilized foam is a silicone gel,which can produce a reduction in the visibility of the scar. Thestabilized foam provides softness and stability required by the siliconegel and allows a therapy to treat the scar for a reduction ofvisibility.

Typically, the silicone gel is cast or adhered onto one surface of thefoam, which is then cut, if required, to the required shape to cover thescar.

The silicone gel layer can further have at least one active selectedfrom at least one vitamin and at least one antimicrobial for assistingin maintaining skin health. Preferably, the stabilized foam is cut to ashape and size sufficient to cover the scar.

The stabilized foam according to the present invention provides anattractive alternative to adhesive coated PVC foams that are suitablefor use in the medical adhesive coated foam markets.

The Examples that follow are illustrative of the present invention. Theyshould not be construed as being limiting in any manner.

EXAMPLE 1

A cross-linked closed cell polyolefin foam sourced from Voltek, a div.of Sekisui America Corporation. The foam is a 6-lb/cubic foot densityfoam that is extrusion coated with a linear low density polyolefin(LLDPE) stabilizing layer on one side. The color is a medium tan or“flesh” color and the total foam thickness is 0.023 inch. This extrusioncoating is 0.002 inch thick and is corona treated to assist in firmanchorage of the adhesive layer. Following extrusion coating, thecombined thickness is approximately 0.025 inch. The release liner is a42-lb/ream bleached Kraft paper, available from SilTech division ofTechnicote, which has been coated with a silicone release coating on oneside. The adhesive is a conventional block copolymer synthetic rubberhot melt from HB Fuller and is applied via a melter and gear pump thatdelivers the adhesive to a slot coating die. The die is from May Coatingand it is set up for direct contact or proximity coating against thesilicone liner.

The adhesive is melted to 350 F, pumped to the die and extrusion appliedonto the silicone side of the release liner at 0.002 inches at about 250fpm. The liner with adhesive and the stabilized foam are joined togetherwith a set of nip rolls and wound into a roll.

Additional processing typically involves ultrasonic perforation,slitting to width, lamination to other materials and die cutting. Theend use is a first aid finger bandage or dressing. Packaging isgenerally cohesive coated paper or for larger sizes, medical pouchesusing combinations of coated Tyvek, coated paper or film.

EXAMPLE 2

Cross-linked PO foam is manufactured at 0.016 inches thick with adensity of 8-lbs/cubic foot and is extrusion coated with an ultra lowdensity polyolefin film layer at 0.0015 inch thickness. A 0.003 inchpolyester film that has been coated with a fluorosilicone releasecoating for use with silicone adhesives is proximity coated with a DowCorning hot melt adhesive formulated with silicone.

The stabilized foam, adhesive layer and silicone release liner are allbrought together in a nip between two rollers and the adhesive transfersto the stabilized foam. The assembly is rotary die cut and is useful forEKG grounding pads.

If required for a grounding pad application, a conductive material suchas carbon black, carbon film or carbon fibers can be added to the foam,stabilizing layer and/or adhesive layer. The stabilizing layer allowsthe production of a thin and soft foam pad with the integrity requiredfor die cutting and converting.

If the silicone adhesive used above has been compounded with an “active”such as an antibiotic, antimicrobial, pain reliving agent, or drug suchas nicotine, the end use product is essentially a “drug delivery system”or transdermal patch.

EXAMPLE 3

Cross-linked PO foam is manufactured at 0.031 inches thick with adensity of 6-lbs/cubic foot and is extrusion coated with a LLDPE filmlayer at 0.002 inch thickness. A liquid acrylic adhesive in a solvent,Gelva 2999 from Solutia, is reverse roll coated onto 53-lb Kraft releaseliner supplied by SilTech. The solvent is driven off as the coated linertravels through a heated oven. As the coated liner exits the oven, it ismarried to the stabilized foam with a set of rollers. Following slittingto width and perforation via the hot needle system, the laminate isconverted into finger bandages and tape.

EXAMPLE 4

Cross-linked PO foam is manufactured at 0.023 inches thick with adensity of 6-lbs/cubic foot and is extrusion coated with a HDPE filmlayer at 0.002 inch thickness. Either side can be treated with anadhesion promoter, Tyzor sold by DuPont.

The stabilized foam is processed through a horizontal oven with thetreated side facing upwards. A mixture of two-part silicone elastomer,Dow Corning, is prepared and coated onto the treated side with athickness of 0.005 inch thick. The assembly is processed through a heattunnel oven with a 3-minute dwell at 225 F. The silicone componentsthermally react and cure to form a very soft and gel-like coating.

A fluorosilicone coated polyester film is used as a release liner andfor protection of the silicone gel surface. This coating adheres to theskin with gentle adhesive action and is easily removed, even from hair.

This product can be slit and die cut into large pads or covers that mayincorporate an absorbent pad positioned as an island on the dressingleaving an exposed adhesive edge to bond to skin. Dressings or covers ofthis design are used to protect a wound, incision, tube or port in theskin from contact with water while taking a shower or in Hydrotherapy.Typical sizes range from 4 inch×4 inch to 12 inch×16 inch withrectangular or rounded corners. This product is durable and can bewashed in water to clean and reused.

EXAMPLE 5

A product identical to the above example is made with the silicone gelelastomer coating produced at 0.025 inch with a fluorosilicone liner.Following die cutting and packaging, the silicone gel is used as scartherapy or treatment for the reduction of visibility of hypertropic orKeloid scars. The use of silicone gel for this application is wellaccepted however the use of stabilized foam allows both a costreduction, when compared to silicone gel coated onto a silicone rubberor urethane films, and a pleasing appearance of the product. Theconformability and flexibility of the foam is useful in thisapplication.

It should be understood that the foregoing description is onlyillustrative of the present invention. Various alternatives andmodifications can be devised by those skilled in the art withoutdeparting from the present invention. Accordingly, the present inventionis intended to embrace all such alternatives, modifications andvariations that fall within the scope of the appended claims.

1. A stabilized foam comprising: a crosslinked closed cell polyolefinfoam having a top and a bottom surface; a stabilizing layer disposedonto at least one of said top and said bottom surfaces of saidcrosslinked closed cell polyolefin foam; and an adhesive layer disposedonto at least one of said top and said bottom surfaces of saidcrosslinked closed cell polyolefin foam or onto at least one of saidstabilizing layers.
 2. The stabilized foam of claim 1, wherein saidcrosslinked closed cell polyolefin foam has a thickness about 0.010inches to 0.031 inches.
 3. The stabilized foam of claim 1, wherein saidcrosslinked closed cell polyolefin foam has a density about 4pounds/cubic ft (pcf) to about 20 pcf.
 4. The stabilized foam of claim1, wherein said stabilizing layer comprises a material selected from thegroup consisting of: HDPE, LLDPE, LDPE, ULDPE, metallocene catalyzedPolyethylene polymer (mLLDPE), vinyl acetate, polyurethane, polyamide,vinyl acetate, silicone gel, and silicone rubber.
 5. The stabilized foamof claim 1, wherein said stabilizing layer is laminated, bonded oradhered to the crosslinked foam.
 6. The stabilized foam of claim 5,wherein said stabilizing layer is bonded to the crosslinked foam film bya method selected from the group consisting of: extrusion, coextrusion,adhesive bonding, thermal bonding, ultrasonic bonding, electrostaticattraction and chemical bonding.
 7. The stabilized foam of claim 1,further comprising one or more additional stabilizing layers.
 8. Thestabilized foam of claim 1, wherein said stabilizing layer has athickness from about 0.0005 inches to about 0.005 inches.
 9. Thestabilized foam of claim 4, wherein said stabilizing layer comprises amaterial selected from the group consisting of: HDPE, LLDPE, LDPE,ULDPE, metallocene catalyzed Polyethylene polymer (mLLDPE) polyurethane,polyamide, vinyl acetate, silicone gel, and silicone rubber.
 10. Thestabilized foam of claim 1, wherein said stabilizing layer furthercomprises an effective amount of at least one pressure sensitiveadhesive material.
 11. The stabilized foam of claim 10, wherein saideffective amount of said pressure sensitive adhesive material is about20 gsm to 70 gsm.
 12. The stabilized foam of claim 1, wherein saidadhesive is a silicone adhesive or a silicone gel and is about 0.005 to0.050 inches thick.
 13. The stabilized foam of claim 1, wherein saidadhesive is in the form of a zone coat, patterned or discontinuousadhesive coating.
 14. The stabilized foam of claim 1, wherein saidstabilized foam is perforated using a technique selected from the groupconsisting of: hot needle, ultrasonic perforation, slitting, die cuttingand die punching.
 15. A method of preparing stabilized foam comprisingthe steps of: providing a crosslinked closed cell polyolefin foam havinga top and a bottom surface; applying a stabilizing layer onto at leastone of said top and said bottom surfaces of said crosslinked closed cellpolyolefin foam; and applying an adhesive layer onto at least one ofsaid top and said bottom surfaces of said crosslinked closed cellpolyolefin foam or onto at least one of said stabilizing layers.
 16. Themethod of claim 15, wherein the crosslinked closed cell polyolefin foamhas a thickness about 0.01 inches to about 0.031 inches and a densityabout 4 pcf to about 8 pcf.
 17. The method of claim 15, wherein saidstabilizing layer comprises a material selected from the groupconsisting of: HDPE, LLDPE, LDPE, ULDPE, metallocene catalyzedPolyethylene polymer (mLLDPE) polyurethane, polyamide, vinyl acetate,silicone gel, and silicone rubber.
 18. The method of claim 15, whereinsaid stabilizing layer is laminated, bonded or adhered to thecrosslinked foam.
 19. The method of claim 18, wherein said stabilizinglayer is bonded to the crosslinked foam film by a method selected fromthe group consisting of: adhesive bonding, thermal bonding, ultrasonicbonding, electrostatic attraction and chemical bonding.
 20. The methodof claim 15, further comprising: applying one or more additionalstabilizing layers.
 21. The method of claim 15, wherein said stabilizinglayer has a thickness from about 0.0005 inches to about 0.005 inches.22. The method of claim 21, wherein said stabilizing layer comprises amaterial selected from the group consisting of: HDPE, LLDPE, LDPE,ULDPE, metallocene catalyzed Polyethylene polymer (mLLDPE) polyurethane,vinyl acetate, polyamide silicone gel, and silicone rubber.
 23. Themethod of claim 15, further comprising: introducing at least onepressure sensitive adhesive material into said stabilizing layer. 24.The method of claim 15, wherein said effective amount of said pressuresensitive adhesive material is about 20 gsm to about 80 gsm.
 25. Themethod of claim 24, wherein said adhesive is a silicone adhesive, gel orrubber.
 26. The method of claim 15, wherein said adhesive is in the formof a zone, patterned or discontinuous adhesive coating.
 27. The methodof claim 15, wherein said stabilized foam is perforated.
 28. The methodof claim 27, wherein said perforation is achieved via hot needle,ultrasonic perforations, slitting, die cutting or die punchingtechniques.
 29. A method of treating a wound, scrape, abrasion or skinpuncture in a patient comprising: contacting said wound and a first-aidfoam finger bandage dressing, butterfly dressing or tape having astabilized foam according to claim
 1. 30. The method of claim 29,further comprising an absorbent, non-adherent and/or antimicrobialfibrous pad placed toward the wound for cleanliness, comfort andinfection control.
 31. A method of maintaining cleanliness of anoperation incision site, suture site, catheter insertion site, or anintentional skin breach site on a patient comprising: treating said sitewith a shower water block system having a stabilized foam according toclaim
 1. 32. The method of claim 31, further comprising an absorbent,non-adherent and/or antimicrobial fibrous pad placed toward the woundfor cleanliness, comfort and infection control.
 33. A method ofmonitoring electrical impulses in a patient during EKG or deliveringelectrical impulses to a patient in a TENS or biofeedback therapy, saidmethod comprising: treating said patient with a foam electricalgrounding pad or a foam device having a stabilized foam according toclaim
 1. 34. A method of softening the scar tissue and collagen depositsin a scar and reducing the raised or keloid portion of the scar overtime comprising: treating said scar with a stabilized foam according toclaim
 1. 35. The method of claim 34, wherein said adhesive layer in saidstabilized foam is a silicone gel for producing a reduction in thevisibility of the scar.
 36. The method of claim 35, further comprisingin the silicone gel layer at least one active selected from the groupconsisting of at lease one vitamin and at least one antimicrobial forassisting in maintaining skin health.
 37. The method of claim 36,wherein said stabilized foam is cut to a shape and size sufficient tocover the scar.